George



UNITED sTATEs PATENT onirica.

GEORGE C. SELFRIDGE, OF NORTH GREENFIELD, NEW YORK.

PUMP.

Specification of Letters Patent No. 29,918, dated September 4, 1860.

To all whom it may concern.'

Be it known that I, GEORGE C. SELFRIDGE, of North Greenfield, Saratoga county, State of New York, have invented a new and useful Improvement in the Construction of Pumps; and I declare the following specification, with the drawing hereto attached as part of the same, to be a full and complete description of my invention.

The drawing represents the interior of my improved pump, in vertical section perspective, the hither half of the chambers or cylinders being removed to show the interior thereof, but the pistons with their rod and valves are represented in full.

The pump consists of two chambers, an upper one A A A A standing by a flanged base 2 upon a lower one B B B B; the area of the diameter of the lower chamber being double that of the upper one, or nearly so, and the length of that part in which the pistons traverse being equal in both. Through the center of these cylinders traverses the piston rod O, O, having at its lower end the piston D fitted to the chamber B, and on its upward part the piston E fitted to the chamber A. The lower piston D is fitted with valves opening upward, (butterfly valves in the drawing). The upper piston E is solid, without valves. It need not be packed, but fitted with tolerable tightness.

An orifice G lnear the upper part of the lower chamber is made to pass the water out from the pump, an exit pipe H being there attached, and extended to the place where the water is to be delivered. Just below the orifice G is firmly placed a valve-seat J across the pump parallel with the pistons. Through its center an orifice is made, for the passage of the piston rod C, which iits snugly therein but with liberty for free motion. On this seat are valves opening upward, (in the drawing butterfly valves like those of the lower piston).

vThe upper chamber is open at top, and the under one is open at bottom, whenever it is intended to place the pump in the bottom of a well, or any place where the lower chamber can be immersed in the reservoir of water to be raised. Otherwise the bottom is to be closed tight and an appropriate tube to be carried from it to the supply water in the usual manner of pump fixtures.

The operation of the pump is thus: The pistons commencing their motion downward, from the tops of their chambers, the upper piston eXpels all air between it and the valve seat J through the eXit pipe H. The upward lifting of the valves of the lower piston pass the air out from the space under to that above the piston. Vhen the pistons have reached the bottoms of their chambers and begin to rise, the valves of J opening upward pass the air out from the lower into the upper chamber and the outer air by the exit pipe, the water from the reservoir occupying the vacuum made below the lower piston as it rises. On the next descent of the pistons the closed valves of J hold the air from following the piston, and consequently retains the water in the chamber B from retreating, the valves of the piston rising and allowing it to pass through the water to the bottom of the chamber. Upon the next rise of the pistons, and during the following stroke of the pump, the lower piston drives the water through the valves of J into the upper chamber which it fills, disposing of (that being its capacity) one half of the water contained between the valve seat J and the lower piston, the remaining half passing out of the eXit pipe H. Upon the next down stroke of the pistons, and during the following strokes of the pump, the water between the upper piston and J being prevented by its closed valves from passing downward is forced out at the eXit pipe. Thus at each up and each down stroke of the pistons one-half of the water raised by the lower piston will flow out at the exit pipe keeping up an equal and uninterinitting discharge.

Should it be desired to secure the water in the pump from freezing, by remaining in the chambers and pipe in cold weather, whenever the lower chamber of the pump itself stands immersed in the reservoir of supply so that the water covers the lower piston, it will only be necessary to permit a slight leakage about the upper piston and the valves of J. The water will then ooze down slowly, and yet the leakage be so small as not to impede the ordinary action of the pump, so that it will not be necessary to water the pistons in order to start the operation of the pump.

`Whenever the pump is placed in the bottom of a well or reservoir with the discharge pipe passing upward above the top of the pump; as soon as the pumping ceases, the water will flow from the pipe downward pressing upon the Water in the upper chamber and forcing it gradually past the unpacked upper piston, filling the chamber and overowing its top until the Water in the pipe falls to its level when it Will cease to flow; the entire upper chamber keeping full until the next operation of pumping.

lWhat I claim, and desire to secure by Letters Patent is- A pump constituted of an upper and lower chamber the upper chamber being of one-half the area of the lower one in diameter placed one atbove the other; having a solid piston moving in the upper, and u4 Vu-lved piston moving in the lower chamber, both attached to the same rod7 and operating in combination with a xed valve-seat and its valves below the discharge orifice, lying between the pistons, the Whole arranged and Working together in the manner and for the purposes set forth in the above speeiicaton.

Signed GEORGE C. SELFRIDGE.

fitnesses JOHN GIFFORD, RICHD. VARIcK DE Wrr'r. 

